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Sunday, September 21, 2014

Teach the ImPACT and not the 'footprint'

Another semester has begun, and I’m
teaching an entry level course in environmental studies for the eighth
consecutive academic year. I enjoy doing so for a number of reasons. One is
that the students coming into first year arrive with a wide array of previous
knowledge and experience. Some have come from high school programs that
provided them a very strong foundation in the natural sciences and in
environmental research, while others are almost petrified at the notion they
might be required to reproduce a chemical formula or calculate anything more
sophisticated than a mean average on the midterm test. Getting this very
heterogeneous group up to the level where they can successfully pursue further
courses in environmental studies (whether they actually choose to do so or not)
is a fun challenge. The students themselves are generally fun, too – they
haven’t yet been worn down by the grind that is an undergraduate degree
program.

It’s also useful for me as a researcher to
be continually reminded of the basic, fundamental concepts on which my
discipline and its understanding of the world are based. Two such concepts I
would like to discuss here are ones that can be found in the first few chapters
of nearly every environmental studies textbook written in the last twenty
years: Paul Ehrlich’s I = PAT model, and Wackernagl and Rees’s ecological
footprint equation. Both represent imperfect attempts to illustrate in simple
terms to a wide audience the scale of human impacts on the natural environment.
One of these I find very useful in teaching undergraduate students, the other
less so.

The one I find most useful is Ehrlich’s I =
PAT model. The letters are as follows: I stands for Impact, P is for
Population, A is for Affluence, and T is for Technology. Sometimes the A gets
replaced by a C for Consumption, an important point to which I’ll return in a
moment. Ehrlich is a professor at Stanford, and is often described as a
neo-Malthusian. For those who don’t know, Thomas Malthus was a British clergyman who in the early 1800s wrote essays warning that human population
numbers cannot grow indefinitely, but are inevitably checked by conflicts,
disease, or limited food supplies. In the late 1960s, Ehrlich wrote a now
well-known book called The Population Bomb, in which he warned that a rapidly
growing human population was in imminent danger of outstripping the world’s
available resources, and would inevitably decline in Malthusian fashion if
urgent steps weren’t taken. Notable is the fact that, at the time Ehrlich was writing,
the global human population was approximately 3.5 billion: roughly half what it
is today, but more than 3.5 times larger than what it was in the days of
Malthus.

The I = PAT model is one way by which
Ehrlich sought to communicate the nature and scale of human impacts on the
environment. The model is more of a conceptual one than a numerical one, and it
argues that the scale of a given population’s impacts is equal to the product
of P * A * T; that is, the number of people in question, multiplied by their
level of affluence and their technological sophistication. The implications are
straightforward. A small but affluent population with the most sophisticated
technology has a much greater potential impact on the environment than a larger
but less affluent population with access to only modest technology. Further, even
a modest increase in population (or any of the other factors) would have a
considerable effect on their overall environmental impact. This is easily
illustrated by imagining that the numerical values for P, A and T were all
equal to 3, meaning the environmental impact equals twenty-seven (27 units of
what, who knows, it’s just 27). Now imagine that over the course of time the
population increases to 4; in that case, the overall impact of the population
jumps to thirty-six. In other words, an increase in population by one unit does
not simply add one unit to the total impact of that population on the
environment (which would be represented by P+A+T) but instead leads to an
increase of nine units of environmental impact.

There are many real-life that suggest
Ehrlich’s model is quite plausible. Take as one example a comparison of
historical greenhouse gas (GHG) emissions between Canada and Mexico. For the
monitoring period 2002-2004, Canada is reported to have emitted an estimated 740 megatonnes of GHGs while Mexico emitted 686Mt. The difference between the
two is less than ten percent. However, the population of Mexico is more than
three times larger than that of Canada, so if we convert GHG emissions to per
capita emissions, we find per capita emissions of Mexicans are roughly
one-third of those of Canadians (7:23 is the actual ratio for that period).
And, if we use gross domestic product (GDP) per capita as a measure of relative
affluence, Canadians are roughly three times more affluent than Mexicans. In
short, Ehrlich’s formula holds: a small population of wealthier Canadians has a
considerably higher impact on the environment (as measured in terms of GHG
emissions) than the much larger but less affluent population of Mexico.

However – and this is a good ‘however’ –
the per capita GHG emissions of Sweden for the same monitoring period (7.86t/person)
were almost identical to those of Mexico. This does not conform to Ehrlich’s
model, because Sweden has a slightly higher per capita GDP than Canada. And the
usual, dubious excuses we use to explain away Canada’s high level of GHG
emissions – we’re a cold climate, industrialized country, etc – no longer make
sense, since the same things apply to Sweden. A more logical explanation is
found in Ehrilch’s formulation itself:

- - it assumes that consumption
levels automatically increase in lockstep with affluence, and

- - it is silent on the fact that
technological improvements can lead to increased consumption, but they can also
facilitate conservation.

As we become more affluent, whether it be
as individuals or as larger groups of people, we have more economic freedom to
make choices. We can choose to consume more, or we can choose to be modest in
our consumption. We have a wider range of technologies to choose from as we
become more affluent. Some technologies are inherently bad for the environment
(disposable Tim Hortons cups and most Chrysler products spring to mind) while
others are inherently beneficial (like bicycles and well-planned public
transportation systems). When it comes to the environmental impacts of GHG
emissions, evidently Swedes have made better choices than Canadians.

A discussion of the I = PAT model is
therefore an extremely useful and clear way of introducing first-year students
to two key themes of environmental studies: the need to find ways of decoupling
consumption from affluence, and the continual need to innovate technologies
that conserve and protect natural resources and ecosystem services. These are
very hopeful messages that encourage students to think to the future in
positive, yes-we-can terms. My students and I therefore go over this model
every year, in the second lecture of the course.

The ecological footprint is something I
find to be conceptually useful but ultimately very negative and discouraging.
Conceptually it’s quite simple: a certain amount of productive space is needed
to provide the resources necessary to meet each individual’s basic needs. But
many of us consume well beyond what is needed to meet our basic needs (and by
contrast, many people around the world have trouble even meeting their basic
needs). Each one of us therefore has a different impact on the planet that can
be measured in rough terms as the relative amount of productive space needed to
support our individual lifestyle and corresponding resource consumption. This
is our ‘ecological footprint’.

The researchers who developed the
ecological footprint idea came up with a method of calculating an estimate of
an individual’s footprint using a series of simple questions. I took the quiz
at www.myfootprint.org recently. It
was quite discouraging, for I learned that if everyone on Earth lived the way I
do, we would need 3.6 Earths-worth of resources to support us all. Which is a physical impossibility, and means that my lifestyle is
unsustainable and, in the long run, inherently damaging to the planet.
Obviously I need to change my ways.

But which ones would I change? The house my
family and I bought is a 20-year-old detached house. I suppose I could sell it
and get a smaller one, like a semi or an apartment, but it would mean moving
out of my neighbourhood entirely, for we own the smallest house for blocks
around. We could replace our high-efficiency natural gas furnace with something
else, but it would cost tens of thousands of dollars for a marginal improvement
in terms of GHG emissions. The house is already fairly well insulated, but a
few older windows could be replaced (and will be in due course). I already
purchase offsets for my electrical consumption through Bullfrog power. As my
students know, I commute most places by bicycle, even in the dead of winter. My
spouse has a car, and needs one; she is a substitute teacher, and public
transportation is so poor in Waterloo region there is no conceivable way she
could get to work without one. I do not propose to ask her to give up her
career simply to lower our ecological footprint a couple notches. I do take an
average of two airplane trips a year for academic purposes, which I suppose I
could cut out. My family and I do not eat out much, and we shop more than most
people at local farmers’ markets, so there's not much I can do there to lessen my environmental impact.

My family and I have done
most of the easy things we can do to minimize our impacts on the environment.
Any further steps would be considerably disruptive, requiring abandonment of
employment (not going to happen) or seeking out accommodations in a
multi-family dwelling that is simultaneously accessible by foot to one of our
places of employment and a year-round source of locally produced foods (am not
sure such a place exists in Waterloo). Which made me wonder whether any
Canadian’s lifestyle might get close to a 1.0 planets-needed score. So I took
the same quiz imagining that I was alone, unemployed, living in a small
downtown apartment, and eating the type of diet someone in that situation might
eat. No car, no airplane holidays, no frills – just the bare essentials of
existence. Kind of like a first year student. Guess what? My ecological footprint was almost exactly the same
(3.69 Earths).

Obviously there is something inherently
flawed in these ecological footprint quizzes. It would appear to be physically
impossible for any Canadian to achieve a score of 1.0. So the question
therefore becomes, why worry about it? If the only people who can have an ecological
footprint of 1.0 are those who live hand-to-mouth in rural areas in developing
countries, why should anyone care about conservation or sustainability? Quite
frankly, I think it would be highly desirable it if everyone in the world lived
a lifestyle comparable to mine. And if that means that over the short run we
need the short term equivalent of 3+ Earths worth of resources to achieve, then
so be it. There is nothing hopeful in the ecological footprint concept, and
there is no useful purpose in getting my students all discouraged and gloomy
about the future. The only message a student can take from the ecological
footprint is that there isn’t much any of us here in Waterloo can do to reduce
our environmental impacts in a meaningful way, so why bother? Since it occupies a significant amount of space
in my students’ textbooks, I mention it in the first week, but I don't spend much time thereafter on the ecological footprint. If I can’t offer my students hope for the future,
then I don’t want to teach.

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About Me

TedX Talk: Beyond environmental refugees

Order my book

My book "Climate and Human Migration: Past Experience, Future Challenges" has been published by Cambridge University Press. Click here to see more or place an order from Cambridge; you can also buy it from Amazon, Chapters, and other online booksellers.

Cornell lecture on climate and migration

If you're interested in seeing the 'long' version of the lecture on which the above TEDx talk is based, please click here to see my invited lecture at Cornell University's International Institute for Food, Agriculture and Development, given in October 2012.